1. Field of the Invention
The present invention relates to a bobbin, and more particularly to a transformer bobbin.
2. Description of the Prior Art
A conventional transformer bobbin 10, as shown in FIG. 1(a) and FIG. 1(b), is composed of a tubular body 20 and a plurality of partition wall 30. Among these, the tubular body 20 is used to accommodate a strip of core, and providing winding of wire formed thereon. The wire includes the wire of primary side(not shown) and the wire of secondary side 60, thereafter called wire 60 for short.
Still referring to FIG. 1(a) or FIG. 1(b), the partition wall 30 is formed on the surface of the tubular body 20 so as to isolate the primary side, the secondary side and a plurality of winding grooves located on the secondary side. The partition wall 30 has a wire guiding notch 31 formed on a section of that. Besides, the partition wall 30 has a flange 33 shown in FIG. 1(a) or a cut corner 35 shown in FIG. 1(b). It should be noted that the flanges 33 and the cut corners 35 are arranged in line, on the same side and the same level. That is, there is no horizontal height difference between the flanges 33 and the cut corners 35.
Still referring to FIG. 1(a) or FIG. 1(b), the secondary side of the tubular body 20 further has 2 pins, including a start terminal 50a and an ending terminal 50b. Among these, the start terminal 50a is used as a terminal from which winding of wire 60 is started and the ending terminal 50b is used as a terminal at which winding of wire 60 is terminated. During the wire 60 extends from the start terminal 50a to the ending terminal 50b, the wire 60 passes the winding groove so as to form windings. Once the winding number of a winding groove conforms to a predetermined value, the wire 60 extends to the next adjacent winding groove to form another winding. In this manner, selectiveness of voltage is formed. For the simplification of drawing, the present invention merely depicts the wire 60 adjacent to the start terminal 50a and the ending terminal 50b. 
Still referring to FIG. 1(a) or FIG. 1(b), during the winding is accomplished and the wire 60 goes back to the ending terminal 50b, it is dangerous if the wire 60 lacks of support and fix since the terminal of the wire 60 is on the opposite of the secondary side and thus far from the ending terminal 50b. The wire 60 is liable to be cut off.
The wire 60 closes to the outer portion having the highest voltage of the winding and short circuit, resulted from undesired displacement, thus is liable to occur even though the wire 60 is still continuous.
Prior art proposed for solving the above problem includes a step of twisting the wire 60 after which extends from the opposite of the secondary side to the ending terminal 50b. The step of twisting is used to strengthen the wire 60 and may solve the problem. However, the step is additional and fails to fix the wire 60.
Alternatively, the above-mentioned flange 33 or the cut corner 35 is provided to support and fix the wire 60. However, the bobbin having the cut corners 35 fails to provide the wire 60 with overall support and any fix. For example, the cut corner 35 can prevent the displacement of the wire 60 caused by the external force form the right side of drawing but fails to prevent the displacement of the wire 60 caused by the external force form the left side of drawing. On the other hand, the bobbin having the flange 33 merely supports the wire 60 but fails to provide fix.
Accordingly, there has been a strongly felt need for a novel bobbin providing the wire with support and fix to solve the above-mentioned problem. Besides, it is desired that the manufacturing process of the transformer using the bobbin is simplified.
The main object of the present invention is to overcome the aforementioned problems. Besides, the present invention omits one manufacturing step compared to prior art.
The present invention includes a tubular body, a first partition wall, at least one second partition wall, at least one third partition wall, a plurality of pins of primary side and two pins of secondary side. The first partition wall is formed on the surface of the tubular body so as to separate the primary side from the secondary side. Additionally, the first partition wall has a first flange having a thinner section used to provide winding of the wire. The second partition walls parallel to the first partition wall are also formed on the surface of the secondary side of the tubular body. Each of the second partition walls has a second breach and a second flange having a second cut corner formed thereon. Each of the third partition walls is interposed between the adjacent second partition walls. The third partition walls has a third breach and a third cut corner formed thereon. The second cut corner and the third cut corner are on the same side but not on the same level.